Roofing system, roof panel therefor, and method of assembling a roof

ABSTRACT

This invention relates to a roofing system, to a roof panel therefor, and to a method of assembling a roof. According to the invention, there is provided a roofing system for a building, the building having four walls, an opposed two of the walls including gable means, the roofing system comprising a number of roof panels which can span the distance between the gable means and be supported thereby and a number of intermediate panels which cannot span the distance between the gable means, the roof panels and the intermediate panels having cooperating surfaces whereby the intermediate panels can be supported by the roof panels. The use of intermediate panels allows the installation of windows into the roof.

FIELD OF THE INVENTION

This invention relates to a roofing system, to a roof panel therefor,and to a method of assembling a roof. The invention is expected to findits greatest utility in relation to roofs for domestic dwellings, andthe following description therefore relates to such use. It may,however, be that the invention also has utility in relation tocommercial or industrial buildings and such applications are notexcluded.

DESCRIPTION OF THE PRIOR ART

Domestic dwellings can have flat roofs or pitched roofs; the inventionrelates to the latter. A pitched roof is traditionally created by anumber of roof trusses comprising wooden frames (typicallypre-fabricated) which are set upon the brick or timber-frame walls ofthe building. A layer of waterproofing material is laid over the trussesand battens are mounted thereupon which support the tiles or otheroutermost roof covering.

The trusses are usually of general triangular shape, with a horizontal(in use) member (which members together define the ceiling of thetopmost storey of the building) and two angled members which define thepitched sides of the roof. In order to support the weight of the tilesetc., most truss designs include intermediate members connecting betweenthe horizontal member and the angled members. It is a recogniseddisadvantage of such truss designs that the intermediate members causeobstructions within the loft space, and render the loft spacesubstantially unusable as living accommodation.

It is becoming increasingly common for newly-built homes to utilise theloft space as additional living accommodation. One factor driving thistrend is that the price of building land is generally increasing, and ahouse in which the loft-space is utilised as an additional bedroom orbedrooms for example can usually be sold for more money than a houseoccupying the same ground area in which the loft-space is not utilised.Also, the planning authorities are increasingly demanding greaterdensity of domestic dwellings upon the available building land (in theU.K in particular the planning requirements have recently changed from13 dwellings per acre to 16 dwellings per acre, for example).

To allow living accommodation in the loft space, so-called “attictrusses” have been developed, in which the triangular shape of the rooftruss is supported by intermediate members which define a living space,i.e. the intermediate members span the areas close to the apices of thetriangle but leave open a large central area of each truss, whichcentral area can be used as living space. However, attic trusses areheavier than traditional trusses and are difficult to handle on site.

Another significant factor for house builders is the cost of materialsand labour used in building domestic dwellings, particularly low-costdomestic dwellings. Whilst the attic trusses allow a home with a givennumber of bedrooms to be constructed on a smaller ground area, andtherefore at greater density, the materials and labour costs ofconstruction are high. It has therefore been proposed to reduce the costof building construction by employing “modular” construction techniquesusing pre-fabricated panels where possible. The desire for suchimprovements was set out for example in the consulation paper“Rethinking Construction—The Report of the Construction Task Force”,published by the U.K. Department of the Environment, Transport and theRegions in July 1998 (ISBN 1 85112 094 7). The Report highlights theadvantages of standardisation and pre-assembly which modularconstruction techniques allow, and cites the ability to construct afully-functioning fast-food restaurant in 24 hours using a high degreeof prefabrication and modularisation.

The possibility of using roof panels in place of the traditional rooftrusses has been recognised, and several companies are manufacturingprefabricated roofing panels. A major benefit of using roofing panels isthat they may be prefabricated to include insulting material, which is anecessary requirement if the loft space is to be used for livingaccommodation.

One company manufacturing roof panels is Unilin Systems of Esselgem,Belgium. This method of construction is suitable for gable-ended roofsand employs a number of purlins which are laid upon the gables to spanthe width of the roof. Typically, there is a ridge purlin at the apex ofthe roof, an eaves purlin adjacent to each set of eaves (i.e. adjacentto the top of the front and back walls of the building) and anintermediate purlin approximately mid-way between the ridge purlin andeach of the eaves purlins. The roof panels each run from top to bottomof one side of the roof, substantially supported by the three purlins.

It is a recognised disadvantage of this type of construction that theintermediate purlins lie within the loft space. Because of theconsiderable weight of the roof panels, and the snow load they must bedesigned to withstand, the purlins are necessarily of largecross-section, and so present a significant obstruction within the loftspace. Also, the intermediate purlin restricts the positioning ofwindows within the roof, i.e. the windows must usually be located abovethe intermediate purlin, and are therefore relatively high in the roof,and higher than would necessarily be desirable. Furthermore, because thepurlins must span the width of the building they are necessarily heavyand difficult to transport and handle on site (whether of wood, steel orcomposite material).

It is another recognised disadvantage that the weight of the panels isat least partly supported on the front and back walls, and tends to pushthose walls apart. It is therefore necessary to ensure that the frontand back walls can withstand the lateral loading applied.

The TRADA Technology Report 2/2000 entitled “Timber Frame:Re-Engineering for Affordable Housing” by TRADA Technology Limited ofHigh Wycombe, England (ISBN 1 900510 25 1) also describes the use ofroof panels, but mounted across the roof. In this way the weight of thepanels is supported by the gable ends (sometimes called the “spandrelpanels”) and not by the front and back walls. Also, no purlins arerequired to encroach into the loft space. This document thereforedescribes a solution to the problems with the Unilin type ofconstruction technique described above. However, the TRADA document isan incomplete disclosure and only sets out the principles of theconstruction techniques, and not the practical details thereof;accordingly, the TRADA document alone does not provide a disclosurewhich would enable a skilled person to construct a roof.

It will be understood that reference has been made above to“gable-ended” buildings, and this term is usually used to describe roofswith the gables at each side. It is however known that some buildingsare constructed with the gables at the front and rear. For all practicalpurposes the roofs of these two types of building are equivalent, and nodistinction between them is drawn in this application.

It will also be understood that modular building techniques are mostsuited to low cost buildings; such buildings typically have simple roofconstructions which are well suited to the use of modular panels.Accordingly, the present invention (and the applicable prior art) isespecially well-suited to roofs which comprise two flat and continuousroof surfaces or sides between parallel gable ends, and may be less wellsuited to more complex roofs. In addition, the distance which each panelmust be able to span between the gable ends is limited by the strengthof the panels, and it is desired that the maximum span be around 5.5metres; such a span is suitable for the vast majority of low-costdomestic housing applications.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a roofing system,and roof panels therefor, which avoids or reduces the above-statedproblems with the Unilin type of construction technique. The presentinvention utilises roof panels which are configured to lie across theroof as in the TRADA disclosure, and seeks to avoid or reduce thepractical problems which lie in the way of a skilled person seeking toput the teaching of that document into effect.

According to a first aspect of the invention, there is provided aroofing system for a building, the building having four walls, anopposed two of the walls including gable means, the roofing systemcomprising a number of panels which can span the distance between thegable means and be supported thereby, characterised in that the gablemeans includes one of a tongue and groove, and in that the ends of thepanels include a respective groove and tongue for location with thegable means.

The provision of a tongue and groove connection between the gable meansand the ends of the panels ensures a positive location for the panels(facilitating ease of construction) and helps to maintain the separationof the gable means in the assembled structure.

Preferably, the groove is located on the gable means and the tongue islocated on the ends of the panels.

The gable means may be a traditional gable constructed from bricks orblocks, with the groove (or tongue) provided therein. Alternatively, thegable means may be a prefabricated panel which is fitted onto the top ofthe wall of the building. The latter has the considerable advantage thatthe brickwork or the like for all of the four walls can terminate at thesame height (i.e. the wall plate level). In such embodiments, theprefabricated gable means can be fitted by the roof installer/assembleras part of the roof construction process.

Preferably, the tongue and groove have inclined sides and a flat bottom.The flat bottom provides a bearing surface supporting at least part ofthe weight of the panel in use. The inclined sides facilitate ease offitment, i.e. the width of the bottom wall of the tongue is less thanthe width of the open end of the groove so that precise location of thepanel above the gable means is not required to ensure cooperation of thetongue and groove.

Desirably, the groove or tongue is continuous across each of the gablemeans. Desirably also the tongue or groove is continuous across the endsof the panel.

Preferably, the roofing system includes a set of intermediate panelswhich cannot span the distance between the gable means. The intermediatepanels have engagement means by which they may be supported by theadjacent panels. The use of the intermediate panels allows window panelsto be fitted therebetween, a set of intermediate panels and windowspanels together spanning the width of the roof in place of a continuous(standard) panel.

The roofing system may be used on individual buildings having gablemeans on opposed walls. Also, it may be used on terraced buildingshaving two end gable means at the opposed ends of the building, and aseries of intermediate gable means located therebetween along theterrace. Usually, the intermediate gable means will lie upon theintermediate walls separating adjacent dwellings in the terrace. In suchembodiments, the system will include intermediate gable means which mayinclude a groove which could be identical to that of the end gablemeans, and panels adapted to span the distance between an end gablemeans and an intermediate gable means and between adjacent intermediategable means. The ends of the panels can be adapted to abut at theintermediate gable means, and may include a partial tongue, so that thetwo partial tongues of the abutting panels together engage the groove ofthe intermediate gable means.

According to a second aspect of the invention, there is provided aroofing system for a building, the building having four walls, anopposed two of the walls including gable means, the roofing systemcomprising a number of panels which can span the distance between thegable means and be supported thereby, characterised by intermediatepanels which cannot span the distance between the gable means, and bycooperating surfaces on the panels and the intermediate panels wherebythe intermediate panels can be supported by the adjacent panels.

Preferably, the cooperating surfaces are complementary step-formations.Preferably also, the cooperating surfaces lie along substantially thefull length of the longitudinal edges of the panels and intermediatepanels.

The invention also provides a roof panel for use in a roofing system asdefined herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example, with referenceto the accompanying schematic drawings, in which:

FIG. 1 shows a cross-sectional view through a roof panel according tothe invention, and includes certain details of a roof in which the panelhas been installed;

FIG. 2 shows a cross-section through the panels which make up a typicalroof, and the roof made therefrom;

FIG. 3 shows a plan view of the panels which make up one side of atypical roof;

FIG. 4 shows a cross-sectional view of the cooperating surfaces ofadjacent panels;

FIG. 5 shows a perspective view of the tongue and groove connectionbetween a panel and an end gable means;

FIG. 6 shows a cross-sectional view of the tongue and groove connectionof FIG. 5;

FIG. 7 shows a cross-sectional view of the tongue and groove connectionbetween two abutting panels and an intermediate gable means;

FIG. 8 shows an end view of an eaves panel;

FIG. 9 shows a perspective view of a building and two prefabricatedgable panels for fitment thereto; and,

FIG. 10 shows a support member for use in a method of constructing aroof according to the invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

FIG. 1 shows a cross-sectional view of a roof panel 10. The panelcomprises a first sheet 12 (which is the innermost sheet in use), and asecond sheet 14 (which is the outermost sheet in use), which areinterconnected by four longitudinal beams 16. Insulating material 18fills the volume between the sheets 12 and 14 which is not occupied bythe beams 16.

It is desirable but not essential that the panels be made from renewableand recyclable materials, and natural materials such as wood arepreferred. In this (preferred) embodiment the beams 16 are of wood, thesheet 12 is of plywood, and the sheet 14 is of fibreboard. The beams 16in this embodiment have cross-sectional dimensions of approximately 50mm by 197 mm, and the sheets 12, 14 are approximately 12 mm thick.

To ensure the required weatherproofing, the outermost sheet 14 includesa weatherproof material, and preferably a “breathable” material; in thisembodiment, therefore, the sheet 14 comprises a sheet of Kronotex (RTM)fibreboard, this material being a one-way “breathable” material adaptedfor use in roofing applications. Though not shown in the drawings, partof the weatherproof material projects beyond the edge of the panel andso can lap over the edge of the adjacent panel in use, to prevent wateringress between the respective panels.

It is also desirable but not essential that the insulating material 18is of natural material, and wool or other natural fibre is preferred.

The panel 10 also includes cooperating surfaces in the form ofstep-formations 20 and 22 along its longitudinal side edges, part of thestep formation 20 being provided by a wooden beam having approximatecross-sectional dimensions of 36 by 72 mm, part of the step formation 22being provided by a wooden beam having approximate cross-sectionaldimensions of 36 by 122 mm. It will be understood that thestep-formations 20 and 22 can interengage, i.e. it is possible to lietwo panels 10 alongside each other with the step-formation 22 of onepanel engaging the step-formation 20 of the adjacent panel.

The panel 10 is manufactured in a standard width (the width being thedistance between the step-formations 20 and 22) of approximately 1200 mm(though other widths, or sets of widths, may be utilised if desired).The panel 10 will be made in a length to suit the particularapplication, the maximum practical length for a panel having thedimensions and materials referred to being around 5.5 metres (which isbelieved to encompass the majority of the low-cost domestic housingmarket). Clearly, if other materials are used in place of the woodenbeams 16, such as purlins of rolled steel or composite material, themaximum practical length may be greater than 5.5 metres. Accordingly, ifa panel length greater than 5.5 metres is desired this can beaccomplished with the present invention by an appropriate choice ofmaterials from which the panel is constructed (and it may also bedesired to use different materials than those specified above for otherreasons).

To provide the structural strength required it is necessary that thebeams 16 be continuous for the length of the panel, and it is preferablethat the sheets 12, 14 are also continuous or effectively continuous. Inthat regard, it is presently only possible in the U.K. to procureplywood sheets up to 2 metres long, but it is possible chemically tobond highly chamferred ends of adjacent panels to produce longer panels.If, for example, the ends are chamferred and bonded over a length ofaround 50 mm the bonded joint can be at least as strong as the basicmaterial.

When assembled into a roof, a series of panels will be used to cover theroof, and then a set of counterbattens 24 (running from top to bottom ofthe side of the roof) will be fitted thereto. Sheets of undersiate paper(not shown) are laid thereover, and the roof is finished with the tilingbattens 26 and tiles (not shown) in conventional fashion. It will beunderstood that since the plywood sheet 12 faces the interior of theloft space, no surface finishing may be required in some applications.However, the joints between adjacent panels would be visible, and iffinishing is required a set of counterbattens 30 may be added, to whichplasterboard 32 can be fitted. Such finishing would have the additionalbenefit of creating a hidden space for the location of services, andservices could be incorporated into the space without needing to cutinto the panels (which cutting may weaken the panels and/or reduce thethermal insulation provided thereby.

The panels which will make up a typical roof are shown in FIGS. 2 and 3.Adjacent the opposed walls which do not have the gable means are locatedeaves panels 40. The eaves panels 40 are shown in FIG. 8, and will bedescribed in more detail later on. The uppermost longitudinal edge ofeach eaves panel has a step-formation 22.

Above each eaves panel is a standard panel 10, the step formation 20 ofthe panel 10 engaging with the step-formation 22 of the eaves panel 40.

Above the standard panel 10 is a set of intermediate panels 44. Asbetter seen in FIG. 3, the intermediate panels 44 are shorter than the(standard) panels 10, and in particular are not long enough to engageboth gable means. Accordingly, the intermediate panels 44 must besupported by the panels 10 to either side, and cannot rely solely uponbeing supported by the gable means. The intermediate panels 44 thereforeinclude a step-formation 20 along each of the longitudinal edges, whichstep-formation 20 can engage (and be supported by) the step formation 22on the adjacent panels 10. The inclusion of intermediate panels 44leaves openings 46 (FIG. 3) therebetween, which openings can accommodatewindow panels (not shown). The window panels are ideally constructedwith top and bottom edges having step-formations such as 20, or edgeformations which can cooperate with and be supported by thestep-formations 22 of the adjacent panels 10. Alternatively oradditionally, the intermediate panels 44 can include step-formations orthe like to support the side edges of the window panels.

Above the intermediate panels is another standard panel 10, and abovethat an apex panel 48 and a set of ridge blocks 38. The dimensions ofthe apex panel 48 are suited to the angle and width of the particularroof, it being expected that different-width apex panels 48 will need tobe provided to suit differently-angled and -sized roofs.

The roof shown in FIG. 2 has a set of intermediate panels 44 on eitherside of the roof, so that windows can be installed in both sides of theroof. In other roofs, windows may be desired only in one side, and insuch embodiments one set of intermediate panels 44 would be replaced bya standard panel 10. Because a standard panel 10 has a step-formation 20and a step-formation 22, it will be understood that replacing theintermediate panels 44 (which have two step-formations 20) with astandard panel 10 will require the step-formations of the panels higherup the roof to be altered. The step-formations of a standard panel 10can be altered (reversed) by rotating the panel through 1800 about anaxis perpendicular to the plane of the panel. The step-formations of theapex panels cannot be reversed, however, and apex panels withstep-formations 20 would need to be provided.

It will therefore be understood that roofs of any width, and with thesides at substantially any angle, with or without windows in both sides,can be constructed from standard panels 10, 22 and 44, with only theapex panels needing to be configured for the particular application.Despite the different apex panels which will be required, however, aconsiderable amount of standardisation can be incorporated into theroofing system of the invention. If more standardisation is required ofthe apex panels, it can of course be decided that both sides of allroofs will have windows and a set of intermediate panels 44, so that allapex panels have a step-formation 22 and it is not necessary tomanufacture apex panels with a step-formation 20.

The large degree of standardisation available with the invention canfacilitate concurrence with the building regulations. Thus, in the U.K.for example bulding regulations stipulate that the stresses on each loadbearing member in a structure be calculated; using standard panelssimplifies those calculations, and means that any re-calculation due toa change in specification may be more easily undertaken.

FIGS. 5 and 6 show the tongue 50 and groove 52 connection between theend of the panels 10 (and also the panels 40, 44 and 48 if desired) andthe gable means 54. In this embodiment the panel 10 carries the tongue50 and the gable means 54 carries the groove 52, but this could bereversed if desired. Also, in this embodiment the tongue 50 is adiscrete tongue located adjacent the corner of the panel (there beingone tongue adjacent each of the four corners); in other embodiments thetongue is continuous across the width of the panel. The groove 52 iscontinuous across the gable means 54 to ensure that the tongues of allof the panels can locate thereinto, whatever their configuration.

The tongue 50 has inclined walls 56 and a flat bottom 60, and the groove52 is correspondingly-shaped. The flat bottom 60 defines the bearingsurface upon which a part of the weight of the panel 10 can besupported. The inclined walls 56 facilitate ease of insertion of thetongue 50 into the groove 52. When the roof is assembled, the weight ofthe panels 10, 40, 44, 48 rests upon the gable means 54, and the fixedlocation of the tongue 50 upon the panels, help to ensure that thespacing between the gable means 54 is maintained, i.e. the roof panels10 (and also perhaps the eaves panels 40 and the apex panels 48) ensurethat the gable means 54 cannot move together or apart. The structure istherefore made more secure against applied loads such as wind loads.

If desired, the inclination on the walls 56 of the tongue 50 can beidentical to the inclination of the side walls 58 of the groove 52;alternatively, the inclinations can differ, which might be necessary ifit is desired that the walls 56, 58 will not foul one another as aresult of manufacturing tolerances.

When the panels have been assembled onto the gable means 54, they may besecured there by way of screws passing through the panel and into thegable means, ensuring that the screw passes through and into thestructural timber of the panel and gable means.

The gable means 54 of FIGS. 5 and 6 is an end gable means, i.e. it isone of the two gable means of an individual building, or it is an endgable means of a terraced building. Because the length of a terracedbuilding (between its end gable means) will usually exceed the maximumpractical length of the panels 10 (etc.), a terraced building will beprovided with intermediate gable means between the end gable means.Since the gable means must support the weight of the roof, it mustitself be strongly supported, and it will typically be arranged that theintermediate gable means are supported upon the intermediate wallsseparating the homes within the terrace (i.e. a terrace of four homeswill have two end walls and three intermediate walls, and a similarnumber of gable means). So that the maximum length of the panels can bemaintained at around 5.5 metres it is desired to abut two adjacentpanels at an intermediate gable means.

Since it is desired to maintain the tongue and groove arrangementbetween the gable means and panels, an exploded cross-sectional view ofa suitable structure is shown in FIG. 7. In this embodiment, each panel110 has a “half-tongue” 150 at its end, which can engage in a groove 152of the intermediate gable means 154. If desired, the groove 152 can beidentical to the groove 52, and the “half-tongues” 150 suitablyconfigured to locate therein. In this embodiment, one function of theinclined walls 156 and 158 is to urge together the abutting ends of thepanels 110, and to ensure that the panels remain in abutment.

The eaves panel 40 is shown in FIG. 8 (and also in FIGS. 2 and 3). Theeaves panel 40 comprises a structure of wood, plywood, fibreboard andinsulating material as are the other panels 10 etc. The eaves panel 40carries lateral beams 62 which are designed to overlie the side walls ofthe building, in known fashion. It is arranged that the eaves panel 40,including the lateral beams 62, is the same thickness as the otherpanels 10 etc., so that together they present a flat surface for theaddition of the counterbeams 24 (see FIG. 1).

The gable means 54, 154 are constructed as prefabricated panels, and aredesigned to be assembled together with the roof panels 10 etc. by theroof installer/assembler. Such prefabricated gable panels have theconsiderable advantage that the brickwork for the building 100 (FIG. 9)can stop at the same level (i.e. the wall plate level) for each of thefour walls.

Alternatively, the gable means may be constructed out of brickwork orblockwork, the bricks or blocks being continued beyond the wall platelevel for the gables. This alternative arrangement has a knowndisadvantage in that the bricklayer must stop laying bricks at the wallplate level in any event whilst other construction work in undertaken,and must then continue the brickwork or blockwork for the gables at alater time; it is not always convenient or efficient for the bricklayerto do this, and a system which allows all of the brickwork to beundertaken as an uninterrupted operation is highly desirable.

The gable means 54, 154 is a panel of triangular shape (the shape of thegable means determining the shape of the roof), and may if desired beconstructed of wood beams and plywood and fibreboard sheets as are thepanels 10 etc.

FIG. 10 shows a part of the building 100 with the roof being constructedin accordance with the invention, the roof being mounted upon spandrelpanels 54 (only one of which is shown) which are themselves mounted uponthe brickwork of the building 100 as in the embodiment of FIG. 9.Despite being secured to the brickwork in known fashion, it will beunderstood that prior to location of the panels 10 etc. the spandrelpanels 54 are liable to sideways movement caused by winds for example.In a method according to the invention a support member 70 is used tosecure the spandrel panel 54 in position until the spandrel panel hasbeen secured by one or more fitted panels 10 etc.

It is a particular feature of the support member 70 that it can befitted from around the height of the top of the brickwork of thebuilding 100, and the fitter does not need to access the top of thespandrel panels themselves. Clearly, there is a considerable advantagein terms of health and safety if the fitter only need access to thislower height on the building site.

The support member 70 includes a cup-shaped bracket 72, a mounting plate74, and a bracing member 76 joining the bracket 72 to the mountingplate. The cup-shaped bracket 72 is adapted to be placed over the top ofthe spandrel panel, one side wall 80 of the bracket engaging one side ofthe spandrel panel 54 and the other side wall 82 engaging the other sideof the spandrel panel. It is not necessary that the side walls 80,82 area tight fit upon the spandrel panel, and indeed the support member 70 iseasier to fit if there is some freedom therebetween; it is expected thata few millimetres of clearance is all that is required to facilitatefitment and yet restrict the spandrel panel to movements within thetolerance allowed by the cooperating tongue 50 and groove 52. Ifdesired, to increase ease of fitment further, the extreme ends of theside walls 80,82 can be internally chamferred if desired.

The mounting plate 74 has a number of apertures (not shown) to receivefixing means such as screws or nails by which it may be fixed to a joist84.

The mounting plate 74 is connected to the brace member 76 by a pivot 86,and the brace member is connected to the bracket 72 by another pivot 88.The pivots 86, 88 allow limited articulation between the bracket andbrace member and the mounting member and brace member, respectively.Accordingly, it is possible to fit the bracket 72 at any position of thespandrel, the higher up the spandrel 54 the bracket 72 is fitted (i.e.the nearer the apex of the spandrel panel 54) the greater the angle ofthe brace member 76. The hinges 86, 88 are adapted to allow sufficientarticulation for fitment to the highest and lowest parts of the spandrelpanel 54.

In practice, it is expected that two or more support members 70 would befitted to each spandrel panel to provide the support required. Clearly,a greater number of support members 70 can be used when conditionsrequire, such as when the roof is being constructed in a high wind, forexample.

Whilst the pivot 88 in particular allows a considerable degree ofarticulation between the brace member 76 and the bracket 72, it isdesired that the pivot have sufficient friction that the fitter canplace the bracket 72 in a chosen position relative to the brace member76, and the bracket 72 will retain this position, i.e. the weight of thebracket tending to force the bracket to pivot downardly is less than thefrictional force maintaining it in position. This allows the fitter tohold the support member 70 adjacent the mounting member 74 andmanipulate the bracket 72 over the spandrel at the chosen height. It isnot necessary that the fitter choose the angle of articulation exactlysince by manipulating the bracket when this engages the spandrel panel54 the fitter can ensure that the articulation is correct to allow theside walls 80, 82 to engage respective sides of the spandrel panel.

When the bracket 72 has been placed over the chosen part of the spandrelpanel 54 the mounting member can be secured to a joist 84 of thebuilding. To allow fine adjustment, in case the spandrel panel 54 is notheld precisely vertical during fitment, the brace member 76 is in twoparts which are held together by a collar 90, the two parts of the bracemember 76 having opposite threads and the collar 90 beingcorrespondingly threaded whereby rotation of the collar in one directionreduces the length of the brace member (and moves the bracket 72 towardsthe mounting member 74) and rotation of the collar in the other directonincreases the length of the brace member (and moves the bracket 72 awayfrom the mounting member 74).

It will be understood that one or more support members 70 can be fittedto the spandrel panel whilst this is still supported by the crane whichlifted the spandrel panel into place, so that the spandrel panel 54 isonly released from the crane when it is adequately supported.

A major advantage of the roof system according to the invention is thatsubstantially all of the weight of the roof is supported by the endwalls (and intermediate walls if present) of the building. Accordingly,each dwelling requires no internal walls to provide support for theroof. If in due course it is required to renovate the dwelling theentire interior (including any non-supporting internal walls) may beremoved and replaced without the roof needing also to be removed.

As above indicated, it is preferable that the roof panels be made ofrenewable and recyclable materials, but this is not essential. Parts orthe panels can for example be made of metals such as steel or aluminium,or composite materials such as reinforced plastics and fibreglass. Itwould for example be possible to use a timber, metallic or compositeskin over a framework of any suitable timber, metal or compositematerial. Also, whilst only certain timber materials have been describedherein, it will be apparent that other timber materials could be used,such as any of the many available proprietary laminated timber materialsfor example. Also, structural I-beams are known to be made of a materialcalled “OSB”, and beams of this material may be utilised in the roofpanels. Furthermore, whilst in the foregoing disclosure the structuralstrength of the panel comes from the timber framework with theinsulating infill providing little or no stuctural strength, foammaterials are available which provide insulation and also rigidity, andsuch materials may be used to provide structural strength for the panel.

1. A roofing system for a building, the building having four walls, anopposed two of the walls including gable means, the roofing systemcomprising a number of roof panels which can span the distance betweenthe gable means and be supported thereby and a number of intermediatepanels which cannot span the distance between the gable means, the roofpanels and the intermediate panels having cooperating surfaces wherebythe intermediate panels can be supported by the roof panels.
 2. Aroofing system according to claim 1 in which the cooperating surfacesare complementary step-formations.
 3. A roofing system according toclaim 1 in which the cooperating surfaces lie along substantially thefull length of the longitudinal edges of the roof panels and theintermediate panels.
 4. A roofing system according to claim 1 in whichthe roofing system includes at least two roof panels and at least oneset of intermediate panels, the set of intermediate panels beingarranged between two roof panels.
 5. A roofing system according to claim1 including two eaves panels, the eaves panels each having complementarycooperating surfaces for engagement with one of the roof panels.
 6. Aroofing system according to claim 1 including two apex panels, the apexpanels each having complementary cooperating surfaces for engagementwith one of the roof panels.
 7. A roofing system according to claim 1 inwhich the gable means includes one of a tongue and groove, and in whichthe ends of the roof panels include a respective groove and tongue forlocation with the gable means.
 8. A roofing system according to claim 7in which the groove is located on the gable means and the tongue islocated on the ends of the panels.
 9. A roofing system according toclaim 7 in which the tongue and groove have inclined sides and a flatbottom.
 10. A roofing system according to claim 7 in which the groove iscontinuous across the gable means or roof panel.
 11. A roofing systemaccording to claim 10 in which the tongue is continuous across the endsof the roof panel or gable means.
 12. A roofing system according toclaim 7 for use on a terraced building having two end gable means at theopposed ends of the building and a series of intermediate gable meanslocated therebetween along the terrace, the intermediate gable meansincluding a groove, the roof panels being adapted to span the distancebetween an end gable means and an intermediate gable means and betweenadjacent intermediate gable means, the roof panels including a partialtongue, the two partial tongues of abutting roof panels togetherengaging the groove of an intermediate gable means.
 13. A roof panel foruse in a roofing system as defined in claim
 1. 14. A method ofassembling a roof of a building, the building having four walls, anopposed two of the walls including gable means, the method including thestep of fitting a number of roof panels which can span the distancebetween the gable means and be supported thereby and the step of fittinga number of intermediate panels which cannot span the distance betweenthe gable means, the roof panels and the intermediate panels havingcooperating surfaces whereby the intermediate panels can be supported bythe roof panels.
 15. A method according to claim 14 in which the gablemeans comprise spandrel panels mounted upon the brickwork of thebuilding, the method including the step of supporting the spandrelpanels with at least one support member, the support member havingbracket means adapted to locate upon a part of the spandrel panel,mounting means adapted for mounting upon a joist of the building, andbracing means connecting the bracket means to the mounting means.
 16. Amethod according to claim 15 in which the support means has a firstpivot means between the bracket means and the bracing means and a secondpivot means between the mounting means and the bracing means.
 17. Amethod according to claim 15 in which the bracing means is adjustable inlength.